JP2015136859A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer comprising a suction hole for attaching a record medium to a platen, taking in ambient air, and capable of preventing increase of power consumption due to loss of heat for heating the platen and cooling of the platen when the ambient air is sucked from the suction hole of the platen and the ambient air is discharged outside.SOLUTION: Air sucked from a suction hole of a platen 6 is made pass through a filter 16 for removing mist, then the air is moderately heated by air heaters 18, 19, and the air is blown to a platen from a position higher than that of the platen at an upstream side of a transport direction of a record medium 25 of the platen.

Description

  The present invention relates to an inkjet printer.

  2. Related Art Ink jet printers that record images by ejecting ink onto recording media such as recording paper and resin films are widely known. Ink jet printers use various types of ink depending on the application, for example, solvent ink using an organic solvent as a main solvent, ultraviolet curable ink cured by ultraviolet rays, and thermosetting ink cured by heat. .

  In addition, there is a desire to quickly move to the next work process, such as lamination for protecting the printed surface after printing, or cutting to a desired size after printing, and it is necessary to dry the ink quickly. In order to meet these demands, a method for solving the problem depending on the characteristics of the ink, such as an ultraviolet curable ink and a thermosetting ink, has been considered.

  On the other hand, an ink using an organic solvent is advantageous in that it has a good fixability to a resin film such as a vinyl chloride film, and a recorded material resistant to abrasion can be obtained. Therefore, it is desired that this type of ink also has good drying properties. In view of this, there has been adopted means for discharging the ink while the recording medium is heated moderately and for quickly drying the solvent after recording the image on the recording medium. For example, the platen, the paper guide at the front stage of the platen, the paper guide at the rear stage of the platen, and the like are heated and the recording medium is transported over them to ensure the drying property.

  In addition, in an inkjet printer, it is desired to record with high image quality. Therefore, it is necessary to keep the printing surface flat and perform recording without reducing the ink landing accuracy. For example, an adsorption unit is provided on a flat platen, and the printing surface is kept flat by adsorbing the recording medium to the flat platen. Some suction means sucks air from a suction hole provided in the platen by a suction fan, discharges the air to the outside of the housing, and causes the platen to suck the recording medium. Further, for example, in the suction means described in Japanese Patent Application Laid-Open No. 2010-201681, air is sucked by a suction fan from a suction hole provided in the platen, but the air sucked by the suction fan is outside the casing. Is configured to be returned to the housing without being discharged.

JP 2010-201681 A

  When ink is ejected from an ink jet head, the ink does not adhere to the recording medium, but behaves as ultrafine droplets, and ink mist may be generated. When ink mist adheres to the recording medium, the image quality is adversely affected. When air is exhausted outside the housing by the adsorbing means, the air pressure inside the housing is reduced, and the air outside the housing flows from the gap. For this reason, the temperature in the housing acts in the direction of decreasing. In addition, since the air flow is fast in the suction holes of the platen where the recording medium does not cover, the temperature of the platen near the suction holes is significantly reduced. In order to keep the platen at a constant temperature against temperature drop, it is necessary to apply power to the platen heater as much as that. In addition, the heating temperature may not be constant.

  On the other hand, when air is returned to the housing without exhausting outside the housing, deterioration of image quality due to ink mist becomes a problem. In addition, since the air flow is fast in the suction holes of the platen where the recording medium does not cover, the temperature of the platen near the suction holes is significantly reduced. Further, since air is circulated in the housing, there is a problem that the temperature may be excessively increased unless the circulated air is cooled, and temperature control is difficult. Although the temperature of the platen needs to be appropriately heated, there are some parts such as a recording head that are not desired to be kept at a high temperature depending on the parts. In addition, when the platen is cooled, the power consumed by the heater placed on the back of the platen increases, it takes too much time to heat the platen to an appropriate temperature, and the temperature varies depending on the position of the platen. In some cases, there arises a problem such as a difference in ink fixing and a deterioration of image quality.

  An ink jet printer according to the present invention has a plurality of nozzles, a recording head for ejecting ink from the nozzles to a recording medium, and a reciprocating movement in a direction crossing the transport direction of the recording medium by mounting the recording head A carriage that is disposed opposite to the lower surface of the carriage, holds the recording medium, a recording medium heating unit that heats the recording medium, a suction hole provided in the platen, and the suction hole A suction fan that sucks air; a transport unit that transports the recording medium; a discharge port that discharges air sucked from the suction hole by the suction fan into the housing; and air sucked from the suction hole In an inkjet printer having a duct leading to a discharge port, the outside air suction means for sucking air outside the housing, and the suction fan Exhaust means for discharging the air sucked from the suction hole to the outside of the housing, and air sucked from the suction hole by the suction fan is supplied to the discharge port or sucked from the suction hole by the suction fan. Switching means for switching whether the discharged air is discharged out of the casing from the exhaust means.

  Reduces the temperature drop inside the inkjet printer casing, saves power supplied to the heater that heats the recording medium, reduces the time required to raise the casing to the specified temperature, and maintains a uniform temperature on the platen Can be realized.

FIG. 1 is a diagram illustrating an example of a gas flow in an inkjet printer. FIG. 2 is a cross-sectional view from the side of an example of an inkjet printer. FIG. 3 is a diagram illustrating another example of the gas flow in the ink jet printer. FIG. 4 is a cross-sectional view from the side of another example of the inkjet printer. FIG. 5 is a block diagram of the ink jet printer. FIG. 6 is a flowchart for explaining the operation of the ink jet printer. FIG. 7 is a diagram illustrating an example of air circulation of the ink jet printer. FIG. 8 is an external view of the ink jet printer.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a gas flow in an inkjet printer. FIG. 2 is a cross-sectional view from the side of an example of an ink jet printer. The flow of air will be described together with the schematic configuration of an example of the inkjet printer 1 using these drawings.

  The housing 2 constitutes the exterior of the inkjet printer 1. The recording head 5 is an ink jet head that ejects ink. The recording head 5 is mounted on the carriage 4 and reciprocally scans the upper side of the recording medium 25. The interval between the recording head 5 and the recording medium 25 is about 2 mm. Four recording heads 5 corresponding to inks of four colors of black, cyan, magenta, and yellow are mounted on the carriage 4. A color image can be recorded on the recording medium 25. The ink color may be five or more. In that case, the recording head 5 corresponding to the number of ink colors is required. The recording medium 25 is conveyed while being attracted to the flat platen 6. An image is recorded by ejecting ink from the recording head 5 onto the recording medium 25 supported on the platen 6. The recording head 5 is provided with 180 nozzles per inch, and one recording head 5 is provided with about 500 nozzles. In order to make the distance from each nozzle to the recording medium 25 equal, the platen 6 has a flat portion that is equal to or larger than the width of the nozzle.

  The carriage 4 is guided by the rail 3, which is a linear rail, and reciprocally scans in a direction intersecting the conveyance direction of the recording medium 25. In this example, the direction is a right angle. The carriage 4 is fixed to the belt 7. The belt 7 is wound around a motor 8 and a pulley 9. The motor 8 is driven to reciprocate along the rail 3. The position of the carriage 4 can be detected by detecting the linear scale 10 arranged along the moving direction of the carriage 4 with the encoder 26.

  The platen 6 is provided with a plurality of suction holes and communicates with a platen lower duct 11 at the lower part of the platen 6. The lower platen duct 11 is connected to a suction fan 17 and sucks air from the suction hole by the suction fan 17. Further, the ink mist sucked from the housing 2 is removed by the filter 16. The filter 16 is disposed between the suction hole and the path of the suction fan 17. The filter 16 and the suction fan 17 are disposed on both end sides of the platen 6. The sucked air passes through the ducts 12 and 13 and is exhausted from the nozzle 24. The switching means 14 is disposed on one side of the platen 6 and the switching means 15 is disposed on the other side of the platen 6. Switching means 14 and switching means 15 are connected to duct 12 and duct 13, respectively. Heating means 18 and heating means 19 are disposed between the switching means 14 and switching means 15 and the nozzle 24 to heat the air flowing through the ducts 12 and 13.

  The switching means 14 controls whether the air sucked from the platen 6 side is exhausted to the duct 12 side or exhausted from the exhaust means 21 side. At this time, when exhausting from the exhaust means 21 side, control is performed to suck air from the outside air suction means 20 and exhaust it to the duct 12 side. The switching means 15 controls whether the air sucked from the platen 6 side is exhausted to the duct 13 side or exhausted from the exhaust means 23 side. At this time, when exhausting from the exhaust means 23 side, control is performed to suck air from the outside air suction means 22 and exhaust it to the duct 13 side. In this way, it is possible to switch between circulating the air in the housing 2 and newly taking in air from the outside. The outside air suction means 22 is preferably one that forcibly takes in air by a fan, but since air is exhausted to the outside of the housing 2, it may be one that is taken into the housing 2 due to a pressure difference.

  Although the recording medium 25 is adsorbed on the platen 6, the air in the housing 2 is sucked from the suction holes of the platen 6 not covered by the recording medium 25. The flow of air in the sucked portion is fast, causing the temperature of the platen 6 to decrease. The sucked air passes through the lower part of the platen 6 and flows toward both sides by the suction fan 17. Air is heated by the heating means 18 and 19 and blown out from the nozzle 24 so that the platen 6 is not cooled too much. The temperature of the platen 6 is prevented from being lowered by circulating warm air instead of cold air from the outside.

  A front paper guide 29 and a rear paper guide 28 are arranged before and after the platen 6 in the conveying direction of the recording medium 25. The recording medium 25 is guided and conveyed in the order of the rear paper guide 28, the platen 6, and the front paper guide 29. Between the rear paper guide 28 and the platen 6, a plurality of transport rollers 27 are arranged along the platen 6 at regular intervals. The conveyance roller 27 is composed of a pair of rollers of a driving roller and a pinch roller pressed against the driving roller. The conveyance roller 27 is sandwiched between two rollers, and the recording medium 25 is conveyed by the rotation of the driving roller. As shown in FIG. 1, the nozzles 24 may be provided in the entire width direction along the platen 6. However, when the air is blown toward the conveyance rollers 27, the air flow is disturbed. Between these, the nozzles may be arranged in the platen direction. Further, the housing 2 is provided with a door 30, and the front end of the door 30 faces the front paper guide 29, and the recording medium 25 is discharged through the space.

  The housing 2 is not a sealed space, but is provided with a gap for the recording medium 25 and the like to pass therethrough, a gap necessary for maintenance and the like. Air enters and exits through these gaps, but the entry and exit of air is suppressed by narrowing the gaps.

  FIG. 3 is a diagram illustrating another example of the gas flow in the ink jet printer. FIG. 4 is a cross-sectional view from the side of another example of the inkjet printer. The example of another structure is demonstrated using these. The platen 6 is divided into five blocks, and a suction fan 17 is provided for each. The respective blocks are a first suction block 34, a second suction block 35, a third suction block 36, a fourth suction block 37, and a fifth suction block 38. The suction fan 17 sucks each block. By dividing into blocks, when the suction holes 33 are all blocked by the recording medium 25, a strong suction force acts on the block, and the displacement of the recording medium 25 can be prevented. In addition, the block in which some of the suction holes 33 are not blocked sucks the recording medium 25 to prevent displacement, although the suction force is weakened. Since air is sucked from the suction holes 33 of this block, the temperature drop of the platen 6 in this portion tends to increase.

  Air sucked by the suction fan 17 from each of the suction blocks 34 to 38 is sent to the duct 11 under the platen. The ink mist sucked from the inside of the housing 2 is removed by the filter 16. The switching means 14 is disposed on one side of the platen 6 and the switching means 15 is disposed on the other side of the platen 6. Switching means 14 and switching means 15 are connected to duct 12 and duct 13, respectively. Heating means 18 and heating means 19 are disposed between the switching means 14 and switching means 15 and the nozzle 24 to heat the air flowing through the ducts 12 and 13. The switching means 14 controls whether the air sucked from the platen 6 side is exhausted to the duct 12 side or exhausted from the exhaust means 21 side. At this time, when exhausting from the exhaust means 21 side, control is performed to suck air from the outside air suction means 20 and exhaust it to the duct 12 side. The switching means 15 controls whether the air sucked from the platen 6 side is exhausted to the duct 13 side or exhausted from the exhaust means 23 side. At this time, when exhausting from the exhaust means 23 side, control is performed to suck air from the outside air suction means 22 and exhaust it to the duct 13 side. In this way, it is possible to switch between circulating the air in the housing 2 and newly taking in air from the outside. The nozzle 31 and the nozzle 32 are directed upward and send air into the housing 2 again. The air flows in the housing 2 so as to circulate in the order from the door direction, upward, rearward, downward, and door direction, and a part of the air is sucked from the suction hole 33.

  In this example, the heater 40 is used to heat the recording medium 25. The heater 40 is provided above the recording medium 25 and is heated from above. The reflector 39 is provided for efficiently irradiating the recording medium 25 with infrared rays. By circulating the air, it is possible to prevent a large amount of cold air from entering from the outside, and thus it is possible to prevent a temperature drop in the housing and a temperature drop of the platen 6.

  Further, for the block through which the recording medium 25 does not pass, the suction of the suction fan 17 is stopped, and the suction amount of the air from the suction hole 33 is reduced, thereby preventing the temperature of the platen 6 from being lowered. This is to control the rotation of the suction fan 17 individually by a control circuit to be described later, and to control the operation of the suction fan 17 with respect to the block not related to the recording medium 25 from the width of the recording medium 25 to be set. Can be realized.

  FIG. 5 is a block diagram of the ink jet printer. The control circuit 41 is a control circuit that controls the entire inkjet printer 1. The I / F 42 is an interface with an external device. For example, it connects to a host PC and inputs data such as image data. The recording means 43 is a means for recording an image on the recording medium 25, including the recording head 5, a mechanism for reciprocally scanning the recording head 5 in the width direction of the recording medium 25, and a mechanism for conveying the recording medium 25.

  The ROM 44 is a non-volatile memory and stores a program for controlling the inkjet printer 1, an initial setting value, and the like. The control circuit 41 operates according to this program. The RAM 45 is a memory used for work memory of the control circuit 41, temporary storage of data, and the like.

  The temperature detection means 46 is a temperature sensor that is disposed in the housing 2 and detects the temperature. The detection result is output to the control circuit 41. The platen heating means 47 is a heater disposed on the back surface of the platen 6 or a heater disposed at a position facing the platen 6, and also heats the recording medium 25. The heater is heated by applying electric power, and the platen 6 is heated to a desired temperature. The platen heating means 47 is controlled by the control circuit 41. The platen suction means 48 is controlled by the control circuit 41. The platen suction means 48 includes the suction fan 17 and sucks air from the suction holes 33 of the platen 6. The air heating means 49 is controlled by the control circuit 41. The air heating means 49 is a heater that includes the heating means 18 and 19 and heats the air sent to the ducts 12 and 13. The outside air intake means 50 is controlled by the control circuit 41. The outside air intake means 50 includes outside air suction means 20 and 22 and exhaust means 21 and 23. The outside air suction means 50 sucks air from the outside of the housing 2 and supplies it to the ducts 12 and 13, and the inside of the housing 2 sucked from the platen 6 side. Air is discharged out of the housing 2. The duct switching means 51 is controlled by the control circuit 41. The duct switching means 51 includes switching means 14 and 15, and supplies air sucked from the suction holes 33 of the platen 6 to the ducts 12 and 13 or discharges air sucked from the suction holes 33 of the platen 6 to the outside of the housing 2. Then, whether to take in air from outside the housing 2 and supply it to the ducts 12 and 13 is switched. That is, it is possible to select whether the air in the housing 2 is circulated or the air is taken from outside the housing 2. When air is taken from outside the housing 2, the air is discharged from the gaps of the housing 2.

  FIG. 6 is a flowchart for explaining the operation of the ink jet printer. First, in step S1, the temperature in the housing 2 is detected by the temperature detecting means 46. Next, in step S2, it is determined whether or not the detected temperature is equal to or higher than a first predetermined temperature. If the temperature is equal to or higher than the first predetermined temperature, the process proceeds to step S3. If the temperature is lower than the first predetermined temperature, the process proceeds to step S5.

  In step S3, the duct switching means 51 is controlled to discharge the air sucked from the platen 6 to the outside of the casing 2 through the exhaust means 21 and 23, and outside the casing 2 through the outside air suction means 20 and 22. The air is sucked and supplied to the ducts 12 and 13. When the temperature in the housing 2 is too high, outside air is taken in to cool the housing 2. Further, in step S4, the air heating unit 49 is controlled to turn off the heaters of the heating units 18 and 19, and the sucked outside air is discharged from the nozzle 24 or the nozzles 31 and 32 without being heated.

In step S5, the duct switching means 51 is controlled to supply the air sucked from the platen 6 to the ducts 12 and 13. Then, the process proceeds to step S6.
In step S6, it is determined whether or not the temperature is equal to or higher than a second predetermined temperature. If it is equal to or higher than the second predetermined temperature, the process proceeds to step S7, and if it is lower than the second predetermined temperature, the process proceeds to step S8. When the air in the housing 2 is circulated, the sucked air is heated and discharged from the nozzle 24 or the nozzles 31 and 32, or is discharged from the nozzle 24 or the nozzles 31 and 32 without being heated. If it is below a certain temperature, it is necessary to warm it positively by heating. Moreover, if it is more than a certain temperature, it will circulate without heating.

  In step S7, the air heating means 49 is controlled to turn off the heaters of the heating means 18 and 19, and the sucked air is discharged from the nozzle 24 or the nozzles 31 and 32 without being heated. In step S8, the air heating means 49 is controlled to turn on the heaters of the heating means 18 and 19, and the sucked air is heated and discharged from the nozzle 24 or the nozzles 31 and 32.

  The values of the first predetermined temperature and the second predetermined temperature are stored in the ROM 33 in advance. The temperature is determined in advance by experiments or the like. The first predetermined temperature is a temperature for preventing malfunction of the device, and the second predetermined temperature is a temperature that prevents the platen 6 from being overcooled. For example, the first predetermined temperature is set to 45 ° C., and the second predetermined temperature is set to 40 ° C. When it becomes less than 40 ° C, it is heated positively, and when it becomes 45 ° C or more, it is actively cooled, and the temperature is kept between 40-45 ° C.

  In addition to the air temperature control described above, the platen 6, the rear paper guide 28, and the front paper guide 29 are provided with heaters and temperature sensors, respectively, so that the control circuit 41 can maintain each of them at an appropriate temperature. Is in control.

  FIG. 7 is a diagram illustrating air circulation in an example of an inkjet printer. A plurality of suction holes 33 are arranged in the platen 6. By sucking air from the suction holes 33, the air pressure in the lower platen duct 11 is lowered, and the recording medium 25 is adsorbed to the platen 6. In FIG. 7, the air flow in the left portion of the platen 6 is shown. It is the same structure of the right side part. Moreover, if the width of the platen 6 is small, it is good also as one structure over the full width of the platen 6, without dividing into right and left like a figure.

  Air sucked by the suction fan 17 from the suction hole 33 passes through the filter 16 to remove ink mist and dust. The air supplied and sucked to the duct 12 by the switching means 14 is switched from the inside of the housing 2 to the outside. Air is heated by the heating means 18. The duct 12 is separated from the root for each nozzle 24. The roots may be common and may be separated from the middle of the duct 12. A resistor is provided in the duct 12 so that the air resistance of each duct 12 becomes constant, so that air is evenly discharged from each nozzle 24. For example, the resistor is provided with a convex portion that narrows the inner diameter of the duct.

  Further, it is preferable that a valve is provided for each nozzle 24 and that the valve is controlled by the control circuit 41 so that air is discharged only from the nozzle 24 related to the portion not covered by the recording medium 25. The platen 6 is mainly cooled because it is a portion that is not covered by the recording medium 25. Therefore, it is difficult to cool the platen 6 by supplying heated air to this portion. Further, the flow of air toward the recording medium 25 is prevented, and the disturbance of the ink ejection direction due to the wind is prevented. Further, the filter 16 is arranged so that air contaminated with ink mist or the like does not enter the housing 2 again.

  FIG. 8 is an external view of the ink jet printer. The ink jet printer 1 supports the housing 2 with legs 52. The leg portions 52 are fixed to both ends of the lower surface of the housing 2. Along the front paper guide 29, the recording medium 25 is ejected in the direction indicated by the arrow 53. In addition, outside air intake means 20 and 22 and exhaust means 21 and 23 are provided at the lower part of the housing 2.

  The present invention can be used in an ink jet printer. In particular, the present invention can be used for a large ink jet printer that records on a wide recording medium.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Housing | casing 3 Rail 4 Carriage 5 Recording head 6 Platen 7 Belt 8 Motor 9 Pulley 10 Linear scale 11 Platen lower duct 12 Duct 13 Duct 14 Switching means 15 Switching means 16 Filter 17 Suction fan 18 Heating means 19 Heating means 20 Outside air suction means 21 Exhaust means 22 Outside air suction means 23 Exhaust means 24 Nozzle part 25 Recording medium

Claims (7)

A recording head having a plurality of nozzles and discharging ink from the nozzles to a recording medium;
A carriage mounted with the recording head and reciprocating in a direction intersecting the recording medium conveyance direction;
A platen disposed opposite to the lower surface side of the carriage and holding the recording medium;
A recording medium heating means for heating the recording medium;
A suction hole provided in the platen;
A suction fan for sucking air from the suction hole;
Conveying means for conveying the recording medium;
A discharge port for discharging the air sucked from the suction hole by the suction fan into the housing;
A duct for guiding air sucked from the suction hole to the discharge port;
In an inkjet printer having
Outside air suction means for sucking air outside the housing;
Exhaust means for discharging the air sucked from the suction hole by the suction fan to the outside of the housing;
Switching means for switching between supplying the air sucked from the suction hole by the suction fan to the discharge port or discharging the air sucked from the suction hole by the suction fan from the exhaust means to the outside of the housing. When,
An ink jet printer comprising:   The inkjet printer according to claim 1, further comprising an air heater that is disposed in the middle of the duct and that heats air discharged from the discharge port.   The filter is disposed in the middle of the duct and upstream of the air heater, and includes a filter that allows the air sucked from the suction hole to pass therethrough and captures ink mist scattered from the recording head. Item 3. The ink jet printer according to Item 2. Temperature measuring means for measuring the temperature in the housing;
If the temperature inside the housing acquired by the temperature measuring means is equal to or higher than a first predetermined temperature, the switching means is controlled so that the air sucked by the outside air sucking means is discharged from the discharge port, Control for controlling the switching means so that the air sucked from the suction hole is discharged from the discharge port when the temperature in the casing acquired by the temperature measuring means is lower than the first predetermined temperature. The inkjet printer according to any one of claims 1 to 3, further comprising: means. The control means further controls on and off of the air heater,
When the temperature in the casing acquired by the temperature measuring means is lower than a first predetermined temperature and higher than a second predetermined temperature, the air heater is controlled to be turned off,
The air heater is controlled to be turned on when the temperature in the casing acquired by the temperature measuring means is lower than a first predetermined temperature and lower than the second predetermined temperature. Item 5. The inkjet printer according to Item 4.   The said conveyance means is provided with several rollers along the direction orthogonal to the said conveyance direction, The said discharge port is arrange | positioned between the said adjacent rollers, The any one of Claims 1-5 characterized by the above-mentioned. The inkjet printer of Claim 1.   The discharge port is formed to gradually narrow toward the tip, the air discharged from the discharge port is discharged toward the platen, and the duct is branched and connected to each of the discharge ports. The inkjet printer according to any one of claims 1 to 6.

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